The study consists of 4 periods: 1) Washout Period (if applicable); 2) a Screening Period of up to 100 days prior to first dose; 3) a 6 month Treatment Period; and 4) a Post treatment Follow-up Period of up to 12 months (if applicable). An electronic diary will be dispensed and training provided to record endometriosis-associated pain, uterine bleeding, and analgesic medication use for endometriosis-associated pain on a daily basis. Pregnancy testing will be performed monthly throughout the study. Subjects will be required to use nonhormonal dual contraception during the study, and will be counseled on appropriate and effective forms of birth control to promote pregnancy prevention.